The Tower of Hanoi is a mathematical puzzle. It consists of three rods and a number of disks of different sizes which can slide onto any rod. The puzzle starts with the disks in a neat stack in ascending order of size on one rod, the smallest at the top, thus making a conical shape. The objective of the puzzle is to move the entire stack to another rod, obeying the following simple rules: Only one disk can be moved at a time. Each move consists of taking the upper disk from one of the stacks and placing it on top of another stack i.e. a disk can only be moved if it is the uppermost disk on a stack. No disk may be placed on top of a smaller disk. With three disks, the puzzle can be solved in seven moves. The minimum number of moves required to solve a Tower of Hanoi puzzle is 2n – 1, where n is the number of disks.

 

Price estimate for a commercial equivalent:  $8 (https://www.amazon.com/Tower-Hanoi-Puzzle-Brain-Teaser/dp/B01MR1QAZL/ref=sr_1_4?ie=UTF8&qid=1491792989&sr=8-4&keywords=towers+of+hanoi)

Savings per replica $6.